Insulating cement



- Patented Oct. 31, 1933 INSULATING CEMENT Adolph V. Leon and Leo H. Roife, Bethlehem, .Pa., assignors to Bethlehem Steel Company, a

corporation of Pennsylvania NoDrawing. Application December 11, 1931 Serial No. 580,488

3 Claims. (01. 10618) Our invention relates to acomposition of mat-. may of course be substituted for the mixture ter having a low thermal conductivity wmcn above referred to. The proportion of sodium carwhen in a plastic state may be readily applied bonate may vary from one half per cent to 2 or to metal or ceramic surfaces. 3% although we have found 1% to be fully ef- 5 The major object of our invention is to pro fective and less damaging to the hands of the 0 vide a material which when spread upon a sure workman who applies it than the higher perface to be insulated will adhere firmly thereto centages. and hardento form a unitary covering of high The constituents of the cement are vmixed in insulating value. A further object is to provide the dry state by tumbling or pugging and the 10 a composition which when it has served its purproduct in this form can be kept indefinitely. 65 pose in one application may be removed, brought For application it is mixed with enough water to a plastic stateagain and reapplied without to form a thin putty and is thrown or trowled ppr a s f it i nal insulating and adonto the surface to be insulated. When the surhesive qualities. face to which it is to be applied is hot it has The essential constituents of our insulating been found beneficial to use more water than for 70 cement are: An insulating body of mineral fibres, a cold surface. a binder for said fibres, and a plasticizer. For on of the main uses of a, cement of this the major p Of the atingbody We prefer kind is to cover the surface of brickwork in to use Slag W001 On cc u t o i s ig i su at certain parts of furnaces and ovens and to stop value and cheapness. To this as a base we add up openings in the brickwork. Since much of 7 from 5 t0 of i We o a e o fi e the brickwork in certain types of furnaces is of which increases the coh re ce o t e fib ou a relatively temporary character, it may result mass. As a binder for the fibrous body and as in considerable economy if the cement applied to an adhesive to promote attachment to surfaces s m can be recovered when the brickwork is to be insulated we use clay. It is desirable that torn down, We find that our e e t nl 80 the y binder be as plastic and unetueus as it has been subjected to a sintering temperature) D Properties being Commonly can be restored to practically its original plasticferred to as fatness. It has been found however ity and adhesiveness by simply adding water and that a clay that is too fat will cause cracking kn ading it.

when the coating harde'ns and we therefore limit Having thus described our invention what we 85 e fatness to that which Dermitsof a Sound claim as new and desire to secure by -Letters coating by mixing a very fat clay such as ben- Patent i tonite with a modifying leaner clay. To increase a 1, An insulating cement composed of slag wool, the plasticity of the mass We add a Small amount asbestos fibre, bentonite, a modifying clay and of sodium carbonate. sodium carbonate. 90

h Preferred formula for the cement is as 2. An insulating cement containing from about follows: 75% to about 90% of a mixture of slag wool Per cent and asbestos fibre containing at least 10% of Slag wool '73 the latter, from about 24% to about 9% of a 40 Long fibered asbestosnfl; l3 mixture of bentonite and a modifying clay of 95 Bentonite 6 which the bentonite does not exceed 75%, and

Medium fat clay '7 from about to about 3% of sodium car- Anhydrous sodium carbonate 1 bonate 3. An insulating cement containing 73% slag From the above outline of the functions of 1,1 asbestos fibre, 6% bentonite, 7 modithe various components it will be evident that fying clay a d 1% anhydrous sodium carbonate. this preferred composition may be altered to ADOLPH V. LEUN. some extent to suit the properties of the available LEO H. ROFFE. materials and the use to which, the cement is to be put. For example, we have found that the proportions of slag wool and asbestos maybe altered within wide limits provided the asbestos content does not fall below about 10%. The total clay constituent may vary from 10% to 25% and a single clay of the necessary fatness 

